14:32:01 [SEVERE] Could not pass event PlayerItemHeldEvent to ItemSlotMachine v1.2.0
org.bukkit.event.EventException
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:427)
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62)
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:479)
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:464)
        at net.minecraft.server.v1_4_R1.PlayerConnection.a(PlayerConnection.java:777)
        at net.minecraft.server.v1_4_R1.Packet16BlockItemSwitch.handle(SourceFile:27)
        at net.minecraft.server.v1_4_R1.NetworkManager.b(NetworkManager.java:290)
        at net.minecraft.server.v1_4_R1.PlayerConnection.d(PlayerConnection.java:115)
        at net.minecraft.server.v1_4_R1.ServerConnection.b(SourceFile:39)
        at net.minecraft.server.v1_4_R1.DedicatedServerConnection.b(SourceFile:30)
        at net.minecraft.server.v1_4_R1.MinecraftServer.r(MinecraftServer.java:589)
        at net.minecraft.server.v1_4_R1.DedicatedServer.r(DedicatedServer.java:224)
        at net.minecraft.server.v1_4_R1.MinecraftServer.q(MinecraftServer.java:485)
        at net.minecraft.server.v1_4_R1.MinecraftServer.run(MinecraftServer.java:420)
        at net.minecraft.server.v1_4_R1.ThreadServerApplication.run(SourceFile:849)
Caused by: java.lang.IllegalStateException: Start block missed in BlockIterator
        at org.bukkit.util.BlockIterator.<init>(BlockIterator.java:169)
        at org.bukkit.util.BlockIterator.<init>(BlockIterator.java:231)
        at org.bukkit.util.BlockIterator.<init>(BlockIterator.java:264)
        at org.bukkit.craftbukkit.v1_4_R1.entity.CraftLivingEntity.getLineOfSight(CraftLivingEntity.java:119)
        at org.bukkit.craftbukkit.v1_4_R1.entity.CraftLivingEntity.getTargetBlock(CraftLivingEntity.java:145)
        at com.DarkBlade12.ItemSlotMachine.Listener.SignListener.onPlayerItemHeld(SignListener.java:71)
        at sun.reflect.GeneratedMethodAccessor70.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:601)
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:425)
        ... 14 more